Drafting apparatus



Nov. 17, 1942. GARDNER DRAF'I'ING APPARATUS 3 Sheets-Sheet 1 Filed NOV. 1, 1939 N0v.17,1942. GARDNER 7 12,302,205

DRAFTING APPARATUS I Filed Nov. 1, 1939 s Sheets-ShetZ q? i" W k 3| Nov. 17, 1942. c, GARDNER DRAFTING APPARATUS Filed Nov. 1, 1959 '3 Sheets-Sheet 5 Patented Nov. 17, 1942 3 Ciaims.

This invention relates to drafting apparatus, and more particularly to a universal drafting ma chine.

Drafting devices of metal heretofore manufactured have embodied serious structural defects which have offset the natural advantages to be derived from the substitution of metal for other materials. A consequence of one of these defects is the difiiculty encountered when utilizing a metal straight edge for inking. The straight edge which is necessarily thin and is invariably constructed to be in close engagement with the surface of the paper tends to cause the ink to flow beneath the rule edge and smear the paper. When the rule edges have been thickened to overcome this defect the device has become heavy and unwieldy, and impractical as a drafting instrument. A further disadvantage of having the thin edge of a metal rule engaging the paper surface is the uncertain support the same provides for other instruments, such as triangles, brought in engagement therewith.

Accordingly, it is an object of the present invention to provide a metal drafting device having a novel construction whereby the above mentioned and other objectionable features of prior art devices made of metal are obviated.

Another object is to provide a novel universal drafting machine.

A further object is to provide a novel metal T-square having a detachable blade adapted to be rolled up and conveniently carried, for example, in a brief case.

Still another object is to provide a novel protractor unit and novel means whereby said unit may be slidably mounted on a T-square, for example.

Another ob-ject is to provide a drafting apparatus having novel paper fastening means associated with the drawing board thereof.

A further object is to provide a novel drafting apparatus made of metal which may be readily,-

rapidly and economically manufactured in commercial quantities and which is durable and efficient in operation.

The above and other objects and novel features of the invention will more fully appear when the following description is read in connection with the accompanying drawings. It is to be expressly understood, however, that the drawings are for purposes of illustration only and are not intended as a definition of the limits of the invention, reference being primarily had for this latter purpose to the appended claims.

In the drawings, wherein like reference characters refer to like parts throughout the several views,

Fig. 1 is a top plan view, with parts broken away, of one embodiment of the present invention;

Fig. 2' is a sectional view taken substantially along line 22 of Fig. 1;

Fig. 3 is a sectional View taken substantially along line 33 of Fig. 1, showing the T-square removed from the drawing board;

Fig. i is a perspective iew, with the parts broken away, of a portion of a T-square blade formed in accordance with the present invention;

Fig. 5 is an exploded perspective View, with parts broken away, showing the manner in which the T-square blade ends may be secured together;

Fig. 6 is a sectional view, with parts broken away, taken substantially along line 6-6 of Fig. 1;

Fig. 7 is a top plan View, with parts broken away, of a supporting plate for a protractor unit operativeiy associated with a T-square blade;

Fig. 8 is a sectional view taken substantially along line 88 of Fig. 7;

Fig. 9 is a top plan view, with parts broken away, of another embodiment of the protractor unit;

Fig. 10 is a sectional view taken substantially along line li2lil of Fig. 9;

Fig. 11 is a sectional View taken substantially along line H-H of Fig. 9; and

Fig. 12 is a sectional view taken substantially along line l2--l2 of Fig. 9.

In the embodiment of the invention illustrated, by way of example, in Figs. 1 to 8 the drafting apparatus comprises a protractor unit l5 slidably mounted on a T-square it which, in turn, isoperatively associated with a drawing board I'Lthe latter being provided with means for fastening a sheet of paper l3, or other drawing material, to the face thereof.

Drawing board if is preferably synthetically formed from a material, such as pressed wood fibre, and is provided close to the edges thereof with a plurality of indentations l9. Novel paper securing means are mounted on said board in said indentations, said means comprising clips 29 formed from a wire having a smaller diameter than the depth of the indentations so that said clips, when flatly mounted, will not project beyond the surface of board ll. Each of clips2ll is, preferably, fabricated from a. single piece of fairly rigid resilient wire, central section 2| of said wire being shaped in the form of a circle and ends 22 of said wire extending radially to approximately the center of the circle and being suitably secured at that point to the drawing board (Fig. 2). Clips 20 are mounted somewhat eccentricaily in indentations l9 which are also preferably circular, the largest space between the clip and the indentation wall being located at the side from which the paper is to be inserted. This prevents the paper from being subjected to the sharp creases and mutilation which might result if the clip was positioned too close to the indentation wall. The paper is inserted between clip 20 and board I7, and is held in position by the resilience of said clip, the latter not extending, when thus operatively utilized, beyond the surface of said board, and therefore not interfering with the movement, for example, of the blade of a T-square over said board.

T-square l 6 which engages board I! is provided with a novel blade 23 secured in a novel manner to a guide shoulder or head member 24 of the well-known and usual shape, said head member being formed preferably of a light metal, such as aluminum. Blade 23 is formed from a strip of flexible metal, such as thin spring steel, being sufficiently thin and flexible to be rolled lengthwise into a circle without being in any way permanently deformed. Means are provided for detachably securing blade 23 to head 24 (Fig. 3) and said means comprise a lug 25, preferably rectangular in shape, welded or riveted to the face of said blade at one end thereof. A recess 26 closely corresponding in shape to the shape of lug 25 is provided in head 24 intermediate the ends thereof, and when said recess receives said lug, blade 23 extends at right angles to the edge of said head. A threaded member 21 is secured to lug 25 to extend perpendicularly therefrom and a thumb nut 28 is adapted to thread thereon to fasten head 24 to blade 23. An opening 29 (Figs. 1 and is provided in the free end of said blade and when T-square I6 is to be carried in a compact form as, for example, in a brief case, said blade is detached from head 24 and bent end to end so that opening 29 receives threaded member 21 (Fig. 5) and the blade is fixed in this position by nut 28.

Blade 23 (Fig. 4) is novelly constructed to facilitate inking and to provide a proper support for triangles and other instruments used in conjunction therewith, said blade having edges 30 thereof raised above the surface of the paper. This is preferably accomplished by pressing edges 30 which are formed integrally with blade 23 above the level of the remainder of said blade, said remainder constituting a central portion 3| adapted to engage and travel along the surface of the drawing paper thus elevating said edges above said paper.

Novel protractor unit l5, preferably formed of metal, is operable in combination with T-square I 6 and in the preferred embodiment thereof illustrated in the drawings is comprised of a pair of blades 32 having straight and parallel ruling edges, said blades being mounted at right angles to each other upon a frame or bracket 33. latter, in turn, is rotatably mounted upon a base plate 34 by means of a cylindrical hub or bearing member 35 (Fig. 6) secured to or formed integrally with said plate, and extending through a circular opening 36 centrally located in said bracket, member 35 being provided with a face plate 37 or other suitable means for maintaining said bracket on said bearing member.

A protractor scale 38 (Fig. 1) having a geometric center which coincides with the axis about which blades 32 pivot is provided on the surface of plate 34, preferably by being engraved thereon. Bracket 33 has an edge 39 thereof concentric with and adapted to overlap a portion of said scale and an index mark 49 is provided on said edge being adapted to indicate the angle between blades 32 and the edge of T-square [6. In order to make it possible to position blades 32 with greater accuracy, it is desirable to have a vernier scale 4| marked on edge 39 for coopera- The tion with scale 38. An arcuate slot 42 concentric with the arc of scale 38 is preferably formed in the portion of bracket 33 adjacent said scal and a threaded member 43 is soldered or otherwise fixed to plate 34 to extend perpendicularly therefrom through said slot. A thumb nut 44 is threaded on said member and is adapted to engage the surface of bracket 33 to fix the latter against movement, thereby fixing blades 32 at any desired angle relative to plate 34. When nut 43 is loosened, slot 42 permits the rotation of bracket 33 through an angle of substantially 90.

In order to readily position blades 32 at any of the commonly used angles, such as 30, 45, and 60, automatic stop means are provided and preferably comprise an arcuate strip 45 secured to or formed with plate 34 and an element 46 fixed, as by rivets 41, to bracket 33. A stop pin 48 is carried by said element and is adapted to engage any one of a plurality of recesses 49 formed in strip 45, each of said recesses being adapted when engaged by said stop pin to position blades 32 at one of the common angles to T-square blade 23. The bracket can thus be fixed against inadvertent movement at selected angles without the use of thumb nut 44. To change the angle, element 46 which is resilient is lifted until pin 43 is raised above the plane of strip 45 and thereafter said element is moved together with bracket 33 and blades 32 to the de-- sired new angle.

Novel means are provided for slidably mounting the above described protractor unit on T- square I6 and it is preferable to detachably mount said unit on said means, although the latter may, in some instances, be formed integrally with said unit. As shown, said means comprise a plate 49 (Figs, 7 and 8) having guideways 59 and 5| formed therewith, said guideways being spaced apart a distance equal to the width of T-square blade 23 and being adapted to slidably receive raised edges 30 of said blade. Accordingly, although plate 49 when operatively positioned on T-square blade 23 is free to move longitudinally, it cannot be lifted from or tilted relative to the blade edges.

Protractor unit I5 is mounted on plate 49 and accurately positioned in a desired relation to said plate by engaging a pair of dowel pins 52 formed with or secured to said plate at the ends thereof and a hub member 53 fixed to said plate intermediate said dowel pins. Openings 54 are provided in plate 34 for engaging said dowel pins and also an opening 55 (Fig. 6) for engaging said hub member, the latter opening being preferably concentric with hub member 35 of the protractor unit. A threaded screw member 56 is formed with hub member 53 and a thumb nut 57 when screwed on said threaded member securely fixes protractor unit l5 on plate 49.

Hub member 53 is suitably positioned on plate 49 to cause blades 32 to be available for drawing lines at the smallest desired angles and to have one of said blades flush with the T-square edge at 0 angle position. Furthermore, the front edge of plate 49 which carries guideway is comparatively short in length and arcuate in shape, being arcuate to keep blades 32 from striking the T-square edge and short to take up a minimum of space in front of said T-square edge. Protractor unit l5 may be detached from plate 49 and used independently thereof.

An alternate embodiment of the protractor unit is illustrated in Figs. 9 to 12, being constructed chiefly of sheet metal which may be rapidly and economically formed, as by stamping, to the desired shape. The unit is designed to consist of a minimum number of parts adapted to be readily assembled and to be manufactured in large quantities. As shown, the unit comprises a single blade 58 pivotally mounted intermediate the ends thereof upon a supporting plate 59, said blade preferably having edges 60 thereof raised in the same manner as edges 30 of T-square blade 23. To pivotally mount blade 58, a circular indentation 6| (Fig. 10) is provided in plate 59 and a screw 62 extends centrally through the roof of said indentation, being secured thereto in any suitable manner, such as by soldering, the head of said screw being located within said indentation and having no portion thereof projecting below the lower surface of plate 59. The upper surface of indentation 6| constitutes a bearing surface upon which blade 58 pivots, the latter having an indentation 63 and an opening 64 therein through which screw 62 extends. A nut member 65 is adapted to be threaded on said screw to prevent inadvertent axial and pivotal displacement of blade 58 once the latter is operatively mounted on plate 59 and set for a desired angle.

A semi-circular protractor scale 56, having a geometric center which coincides with the pivotal axis of blade 58, is located on plate 59, preferably by being engraved thereon, and an opening 66a through which said scale may be viewed is provided in the portion of said blade which is adapted to overlap said scale. An index is carried by said blade to indicate the angle for which said blade is set, and end 68 of the latter is preferably turned at practically a right angle to the remainder thereof to provide a grip whereby said blade may be readily moved to any desired angle.

To automatically stop blade 58 at certain angles, a stop pin 69 is carried by end 63 and openings F0 are suitably located in plate 59 in the path of said pin for receiving the latter and fixing said blade. In the illustrated embodiment, said openings are provided in an arcuate strip II which is preferably formed integrally with plate 59 by being punched therein and blade 58 which engages said strip at one end is thereby inclined slightly to the plane of sai P being thus caused to engage the surface over which it is being used.

In order to provide means whereby the protractor unit can be guided along the straight edge of a T-square or drawing board, the single sheet of material from which plate 59 is preferably formed is bent into a fold so that a portion 12 thereof extends beneath the portion upon which blade 58 is mounted. Portion 12 has edge 13 thereof turned down to be substantially perpendicular to the plane of plate 59 and thereby provides a surface adapted to engage a straight edge and guide the protractor in motion parallel to said edge. When a line is to be drawn parallel to the straight edge with which the protractor unit is being used, blade '58 is adapted to be disposed as shown in broken line position in Fig. 9 with the edge thereof flush with the edge of plate 59.

There is thus provided a drafting device having novel means for fixing a sheet of drawing material thereto and novel apparatus whereby lines may be drawn on said material at any angle. A novel T-square is provided having a blade made of metal, thin and flexible enough to be rolled up and have the ends secured to each other. Despite the thinness of the blade, the latter is novelly constructed to provide a good edge for drawing ink lines and a good support for other straight edged instruments. The quare blade is additionally adapted to have a protractor unit novelly mounted thereon for operation in combination therewith, said protractor unit being made of metal and having novel means for mounting and positioning the blades thereof.

There is also provided a novel protractor unit which is almost entirely formed from sheet metal and which is adapted to be readily and very economically manufactured in large quantities. Novel means for automatically stopping the protractor blade at certain angles and for fixing the blade at any desired angle are additionally provided, being in part integrally formed with the blade and in part with the supporting plate for said blade.

Although only two embodiments of the present invention have been illustrated and described, it is to be expressly understood that the same is not limited thereto. Various changes which will now be apparent to those skilled in the art may be made in the design and arrangement of parts without departing from the spirit and scope of the invention. For a definition of the invention, reference will be had Primarily to the appended claims.

What is claimed is:

1. In a protractor unit for drawing lines at any desired angle to a given straight edge, a supporting plate, means formed with said plate adapted to engage said straight edge and guide said unit in motion parallel to said straight edge, an arcuate strip carried by said plate, said strip having the top surface thereof elevated above the top surface of said plate, and a blade pivotally mounted on said plate, said blade having one end thereof in engagement with the top surface of said strip and being inclined thereby in the direction of the drawing surface over which said protractor unit is used.

2. In a protractor unit, a supporting plate formed from a sheet of deformable rigid material, a raised arcuate strip formed in the upper surface of said plate, a blade pivotally mounted on said plate, said blade carrying a pin adapted to engage one of a plurality of recesses in said strip to fix said blade at a Known angle to said plate, a hat guiding member perpendicular to the plane of said plate and adapted for engagement with a straight edge to serve as a guide for said plate, and a fold in said sheet material integrally connecting said member to said plate.

In a protractor unit, a supporting plate formed from a sheet of deformable rigid material, a raised arcuate strip formed in the upper surface of said plate, a blade pivotally mounted on said plate, said blade having one end thereof in engagement with the top surface OI said strip and being inclined thereby in the direction of the drawing surface over which the protractor unit is used, a hat guiding member perpendicular to the plane of said plate with a straight edge to serve as a guide for said plate, and a fold in said sheet material integrally connecting said member to said plate.

CUMMINGS GARDNER. 

